1. Field of the Invention
This invention relates to glassworking chucks and to glassworking lathes equipped with such chucks.
2. Description of the Prior Art
Scroll glassworking chucks are known for use with glassworking lathes. These chucks typically consist of a chuck body retaining chuck jaws in meshing engagement with a scroll gear coupled to a handwheel which permits opening and closing of the chuck jaws. One disadvantage of the scroll or universal chuck is that the jaws cannot be opened sufficiently far to accommodate large workpieces.
Planetary chucks are also known, typically operating in response to rotation of a ring gear contained within the chuck housing. Pinion gears connected to the chuck arms engage the ring gear and rotate the chuck arms thereby opening or closing the arms depending on the direction of rotation, in response to rotation of the ring gear.
A major disadvantage of the planetary chuck is the need for a key or wrench to open and close the arms of the jaws. Sometimes workers leave that key or wrench in the chuck after placing the workpiece in the chuck and turn on the lathe. This creates a very dangerous situation in that the key or wrench may fly out of the chuck striking the operator and/or the workpiece, thereby resulting in bodily harm to the operator and damage or destruction of the workpiece or both. Additionally, the key or wrench is generally lost in such situations and, resultantly, after the accident, it may be impossible to open the chuck jaws to release the broken or damaged workpiece therefrom.